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Mr.RC-Cam

Maxim's Loss-of-Video-Sync Alarm IC

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And now... Ta-Rah! The latest low-profile Oracle - that can fit neatly in my flight case with 2 receivers. (All I need now are some RCA jacks that stick out 1mm...)

Nice one, mate! That's exactly what I need to do.

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Hi together,

gave Oracle the first try at weekend and was an absolutely success at all ! Have in the moment only two self-made antennas connected (two 8 dBi patches are on the way from BWAV) but videolink was really impressive improved after attaching the Oracle controller. Attached a pic before wiring was finished.

Congrats to the excellent work Mr. RC-Cam !

Cheers,

Erwin

post-6-1185276023_thumb.jpg

Edited by helitron

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Well after a while trying to make a good PCB for my second receiver Airwave AWM 634, yesterday I put it all together and went to my flying club for doing some testing.

I received my Oracle Diversity Receiver for beta testing about 1 1/2 month ago. Shipped real fast and very well packet. Then I began searching for an apropiate box to fix it in it. Doesn´t seem possible to buy it here in Spain, I called RS online Spain and they didn´t have the case with no possibility to bring it here. So I decided on mounting the PCB on a nice flat piece of wood :D.

Another delay was that I was getting black& white picture from my Airwave passing through my video Amplifier, have noticed that oracle has 2 video outputs until couple of days ago. After all time to check it all at home, made all the wiring and conected both Airwave receivers (one with the SMA conector soldered directly to the rx module, and the other one with a proper 50 ohm rf route). Then the surprise came on when I see the oracle outputs a perfect image from both airwave receiver, so I could get rid of my crappy amplifier.

Time to set up, it´s quite easy to program the diversity the way you want, it just needed to pay a little bit of attention.

Set ups:

1. PAL

2.Swicthing alert. ON

3. Low battery alert. ON

4. Low battery alert Voltage. 9.5V

5. 0.5V

6 Switching sensivity. 3

7 Video balance adjustment. DONE

So with all this checked and set it up, yesterday I went to fly. Mounted all this equipment took me about 15 minutes, I decided to use 1 Lawmate receiver with a CP Patch, and 1 Airwave receiver with the SMA soldered directly with the GP Patch, as long as the other Airwave haven´t tried yet flying. The receivers where separated each other about 70 cm measured from the SMA connector and the left one (lawmate was about 20º pointing to the left and the right receiver (airwave) 20º pointing right.

So I took off and the general feeling after a while was much more comfortable than flying with a single receiver. There were zones where I usually loose signal and this time Oracle were handling them nice. But yesterday was a bad day for doing FPV, I made a simple modification on my rc antenna that turned out worst than usual. I was getting a general worst image than usual too. There some days that this happen at my club, gets very noisy and don´t really know why. I suspect that the building I fly close to it, has some 2.4 ghz system operating not every day. I was getting severe r/c glitches and the flight was not really comfortable but I wanted to see the system´s limit, during this glitches about 1.2 km away home I made a sharp turn and lost altitude about 50 m. The video went snow in a sudden, didn´t have time to react and the easy star was gone. It couldn´t survive to this test :P Just kidding.

I drove my car close to the area and the worst thing was that it has fallen over a dense tree area. I could find it thanks to the Bec´s bip. The damages where medium, camera mounting+tilt servo+conector broken. The transmitter cables were cut and the fuse was in front damaged too.

So the overall feeling with oracle was much more comfortable than before, perhaps it had to be set up for yesterday at level 4 or 5 of switching. Sometimes seems that Oracle make the transition a litllte bit slow with a black image in between, it can be apreciated in the video.

And that´s all, I plan to do more testing on it soon and will keep posting the results.

My apologies to Mr.RC-Cam for such this delay on my beta testing.

22710271534.jpg

Oracle Testing -around 80 mb

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One thing I didn´t mention here is that I had a friend close to me looking at the plane and a moment before the last turn he warn me to gain altitude since he didn´t have direct viewing to my plane. There were hills and trees between us and the plane so this is much more the reason I lost signal. Reviewing other videos I have I´ve found that I haven´t gone that far at this low altitude ever. This two reasons are why I lost the signal in a sudden, with no time to react and regain altitude. This time my excess of confidence pushing to the limit my 2.4 ghz transmitter and receivers have cost me a crash. Don´t forget this gold rule:

Don´t flight low with mountains and trees between you and the plane, this will kill fast your reception.

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Don´t forget this gold rule:

Don´t flight low with mountains and trees between you and the plane, this will kill fast your reception.

I don't even fly low and far if there is no obstacle. I've already had enough issues that way.

Edited by Kilrah

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Me too. I always try to keep the height/distance so I can glide back if needed, this normaly means I fly into the wind to be sure of getting back. ;)

Terry

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One thing I didn´t mention here is that I had a friend close to me looking at the plane and a moment before the last turn he warn me to gain altitude since he didn´t have direct viewing to my plane. There were hills and trees between us and the plane so this is much more the reason I lost signal. Reviewing other videos I have I´ve found that I haven´t gone that far at this low altitude ever. This two reasons are why I lost the signal in a sudden, with no time to react and regain altitude. This time my excess of confidence pushing to the limit my 2.4 ghz transmitter and receivers have cost me a crash. Don´t forget this gold rule:

Don´t flight low with mountains and trees between you and the plane, this will kill fast your reception.

Sorry to hear about your crash Wavess. You're lucky to get your plane back and the damage repairable. I like your "Golden Tip"! I just had to adopt the WAVESS rule into my book! :D

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Well after reviewing my test video again I have a couple of cuestions to try to understand Oracle´s behavior.

On minutes 1:42 2:31 2:42 2:58 and 3:58 I think there is a switch between receivers that can be apreciated by a black screen and the an instant black&white picture, then picture goes in color great. At home when I tested I didn´t see this behavior at all (I can´t go and check it again because I´m repairing my video transmitter). What do u think it´s happening here? Is there any way of getting rid of this?

For a lot of users this may be a scenario that will never happen but for me broadband interference is evident on most of my flights. I will have to do a real flying test in the field to be sure how big a problem this is. I would like Oracle to be able to tell that any picture with interference is better than snow. I will be interested to hear of anyone in a similar situation.

It was crossing my mind if I´d have a better picture than the snow I got on the final crash, I doubt it but would like to know if somebody has tried this Terry´s mentioned in an early post.

The V1.4 firmware is available. This has the revised button timing we discussed several weeks ago. It also includes some code to minimize the switching bias towards the Video 1 source

Could you explain a little more the minimazing switch towards the video 1 source?

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Wavess, the problem you quoted me on was for the first beta release of Oracle, the next update cured this problem.

The bias towards video 1 was not a big problem for me, it just ment if both video 1 and video 2 were ok then it would choose video 1.

The video will switch to the other channel as soon as video is lost as long as the other channel has good video. The exact level of loss required can be set to one of five levels. As the video signal is lost it will often go black and white before total loss, this maybe what you can see. Try setting to a higher level to minimise this.

Remember that even with 2 aerials there will be times when niether has a good signal for Oricle to choose.

Terry

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On minutes 1:42 2:31 2:42 2:58 and 3:58 I think there is a switch between receivers that can be appreciated by a black screen and the an instant black&white picture, then picture goes in color great. At home when I tested I didn´t see this behavior at all (I can´t go and check it again because I´m repairing my video transmitter). What do u think it´s happening here?

That occurs if both video sources are bad. Where possible, Oracle picks the best of the two when both are bad.

Could you explain a little more the minimizing switch towards the video 1 source?

As Terry mentioned, if both video sources are good, Vid1 would be chosen. So whenever both video sources were fine, this meant that you would see the Vid1 LED on more than the Vid2 LED. This confused some users since they expected it to be more random in nature. But, it really is not expected to be a problem (I consider it a "cosmetic" issue). On the latest release (V1.4) this bias was eliminated. I can certainly reflash your microcontroller if you forward it to me.

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Well thanks both. I think I´ll have to set up oracle a little bit more agressive to fly over my club. That would explain why I haven´t seen it on the trials I did at home.

The switching towards video 1 is not a problem for me, so I´ll be fine with the version I´ve got.

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An oracle update: I have been building a twinstar seaplane FPV. I was hoping to use a new mobicom900mhz 1.2watt tx, but it has been shelved due to rf interferance and servo jitters. I have aready reported on another thread that my black box osd did not work with th mobicom tx, even though it seemed to work fine with the airwave modules.

I proceded with airwave and the black box, but now I have found that the black box has a problem with the oracle. On first power up, everything works fine, but after 30sec or so, the oracle starts switching, this increases ultill the switching is almost constant. I have tried powering the tx/camera on separate lines, and even separate power from the OSD, thinking maybe it was heat buildup, no luck. I have tried adding extra caps on the video lines, still no help.

The odd part, is that I can not see any problems in the recieved image, the data and picture are sharp and clean.

rapid switching occours even in the lowest sensitivity setting

Any ideas?

I can't fault the oracle, as it works fine as soon as the black box is removed.

Ken

Edited by Lupy

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The OSD is obviously doing something to the video signal the Oracle dose not like. Have you put a scope on it to see whats happening ?

Terry

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I had the same problems with another OSD. I guess the Oracle's sync detector gets fooled by the steep black/white transitions and starts to output garbage sometimes...

My signal wasn't 100% clean so I didn't report anything as it obviously has an impact. The black box should be cleaner though.

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Very odd. I used to have access to a Blackbox OSD, but not any longer. Too bad, since I would have liked to see what you are seeing.

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I supose I could send the Black box to you, I'm not going to use it any time soon. Would like it back at some point of course.

Ken

Edited by Lupy

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Kilrah, what OSD did you use that gave you problems with Oracle? Was the problem the same as Lupy? Have you tried your other OSD's with it?

Lupy, are you using NTSC or PAL video? {BTW, it would be grand if you added your location to your profile.} Is there any chance that Oracle's video mode setting is on the wrong video standard?

Does sensitivity setting "1" work OK with the Blackbox OSD?

I'll try to think up some more questions that could help narrow this down. But, if the Blackbox OSD is indeed disturbing the syncs then this will be a interesting problem to solve.

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It's my development version of the Intelligent Flight OSD. But as I said it had a known problem (I also had some video tearing with some other displays, for example my PC capture card was fine but not the goggles).

The video circuitry has been changed since then, I have the new version but I haven't tried it with Oracle yet.

Trying other OSD's is a nice idea, I might even have a black box left.

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But, if the Blackbox OSD is indeed disturbing the syncs then this will be a interesting problem to solve.

Interesting to solve but blackbox is no longer being produced.

If it helps some, my OSD was a BOB-4 based one, didn´t have any switching issues, just black&white swithing issues but have nothing to do with the problem exposed before.

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Interesting to solve but blackbox is no longer being produced.

So true. My offer to look at the Blackbox OSD was so that I could try to resolve Lupy's problem and get him going. But I agree that the BlackBox is not a huge concern since it is essentially a dead product (it is still for sale though). FWIW, I haven't heard anyone mention it in ages. But having said that, I will still try to help out if I can.

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I've been using the oracle and it works great. The only thing I have been thinking of trying out would be more of them ganged together. An array of 5 antennas would cover 360 and stright up no? I'm thinking I could use 3 oracles and get the 360 degress with 4 antennas and a third oracle to switch the final 2. And judeging from my 2 antennas now they seem to have a wider beam than advertized anyway.

Technically at 70 degree beamwidth I would need 5 antennas but I think 4 would do. The only problem I have is that that would make a heck of a stack of equipment :) I would love to have a nice array controlled by one box. I think it would be better than relying on tracking equipment. Would it be very hard?

I haven't seen schematics for the Ic's but can I channel them together to one final output from 5or 6 recievers instead of 2? Hopefully in one box.... Could a basic stamp monitor RSSI with these ic's and switch between whatever number of antennas?

I need more info about RSSI I guess. Putting on reading glasses......

I've finally learned that the reception offers much better results than amplification so that's where I headed.

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The only thing I have been thinking of trying out would be more of them ganged together.

I haven't heard from anyone that has ganged Oracles. But there is evidence this technique should work since Oracle has been used other diversity receivers.

And judging from my 2 antennas now they seem to have a wider beam than advertised anyway.

Antenna beamwidth pattern specifications simply indicate where their gain has declined -3dB. This is not a "brick wall" sort of issue; most antennas continue to operate far outside their stated beamwidth, but at reduced gain.

Could a basic stamp monitor RSSI with these ic's and switch between whatever number of antennas?

One of the fast Stamp controllers could be used to control a diversity system. Keep in mind that even with RSSI detection, you will be switching the video, not the antenna. That is good too, since microwave antenna switching is difficult.

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